1. Field of the Invention
The present invention relates to crude oil pumping from deep wells with emphasis on long stroke pumping apparatus employing counterbalancing, or counterweighting, for improved efficiency.
Apparatus of the type to which the present invention pertains is in wide-spread usage wherever retrieval of crude oil from deep wells, some of which are 16,000 feet or more, is required. Inherent in deep well pumping is the requirement for an extremely long string of rods, fastened end to end, to extend from a pump down into the well to a depth somewhat below the current crude oil level in the well. Because of the length of these rods, often referred to, collectively, as a sucker rod, relative to its diameter, they have a tendency to stretch when in tension, and upon reversal of the pumping stroke, the shock of the change in direction often results in damage, if not destruction, of the rod somewhere along its length. Needless to say, retrieval of a damaged or broken rod below the earth's surface is a complex and time consuming problem and, therefore, a very expensive problem.
2. Overview Of The Prior Art
In order to alleviate problems inherent in deep well pumping, I, as well as others, have, for several years, sought various means of minimizing damage to sucker rods while providing a smooth, even stroke for delivery of an optimum quantity of oil with a minimum of energy expense. Examples of these previous efforts include my previously issued patents, U.S. Pat. Nos. 3,248,958; 3,345,950; 3,483,828; 4,391,155; 4,651,582, and this current effort. Others who have recognized the value of using elastic belts include Albert, et al. U.S. Pat. No. 4,496,285.